It is known a power control apparatus that controls equipment such as a load provided in a consumer and a distributed power supply, and performs an optimum energy management. Among such power control apparatuses, which intended for a house is called an HEMS (Home Energy Management System).
The power control apparatus described above transmits control information, which is for performing controls such as equipment state confirmation and equipment setting change, to equipment in a predetermined cycle (hereinafter, “predetermined cycle”). The equipment receiving the control information transmits response information corresponding to the control information to the power control apparatus.
Here, in a power control apparatus, when transmitting control information to equipment in a predetermined cycle, an application operating in a higher layer is configured to perform a retransmission control (a retransmission control of an application layer) using a timeout period and a retransmission possible frequency, separately from a retransmission control (a retransmission control of a physical layer) by a communication protocol of a lower layer. In a power control apparatus, since a control of equipment is managed by an application, such retransmission control by an application is necessary.
However, in a radio communication according to an ad hoc network in which a communication path changes dynamically, it is difficult for a power control apparatus to estimate a timeout period used for a retransmission control corresponding to the control target equipment.
Here, it is disclosed a technique for changing a timeout period based on a change of number (number of hops) of relay apparatuses through which control information is relayed from a power control apparatus to control target equipment (for example, referring to Patent Literature 1).